Note: Descriptions are shown in the official language in which they were submitted.
CA 02210442 2003-07-09
A CUTTER HEAD, BORING JIG AND DEVICE AND PROCESS
FOR SEA BOTTOM BORING
Technical Field
The present invention relates to a cutter head for trial borings, a boring
jig for gathering earth samplings in the form of a sea bottom boring jig and a
process for sea bottom boring that is used in earth sampling to collect soil
samples from a defined depth beneath the bore surface.
Background of the Invention
In the past, for trial borings, louvered slide cutters were used which
have two offset pairs of cutting wheels, positioned parallel to the tool's
axis,
which rotate in opposite directions on horizontal axes so that the loosened
earth is
conveyed to the intermediate space between the two wheels, where it is
transported upward by a suction device. These louvered slide cutters include a
frame designed for large volumes and consequently are very heavy. The bore
cross section formed by the tool is necessarily rectangular and in order to
support
the borehole, a support fluid must be poured into the bore hole. An example of
such a support fluid is bentonite.
Such louvered slide cutters are not very suitable for earth sampling
since the support fluid is filled up to the bore bottom and consequently mixes
with the bored earth. A clean analysis of the composition of the bored earth
layer
is thus not possible. Further, the bore cross sections are unnecessarily large
and
the rectangular shape of the bore cross section results in only moderate
inherent
stability of the bore.
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While louvered slide cutters of this type are used by supply ships for
earth sampling below sea level, the maximum reachable bore depth is limited.
Sea bottom sampling such as, e.g., diamond prospecting or the search for other
rare materials, thus often requires the use of excavating buckets. However,
this
process is very imprecise and not particularly efficient.
It is further known to explore the sea bottom with what can be called
tubed worms. While this process makes it possible to reach greater bore
depths, a
boring worm can only be used when boring in relatively soft ground.
Clearly there is a need in the art for a cutter head for trial borings, a
boring jig for gathering earth samplings in the form of a sea bottom boring
jig
and a process for sea bottom boring that may be used in earth sampling to
collect
soil samples from a defined depth beneath the bore surface and to do so in
hard
earth material as well.
Summa .roof the Invention
A primary object of the present invention is to overcome the
aforementioned shortcomings associated with the prior art devices.
Thus an object of the present invention is to provide a cutter head, a
boring jig and a sea bottom boring jig, as well as a process for sea bottom
boring,
that makes it possible to achieve efficient earth sampling to great boring
depths
even when presented with hard earth material.
According to the invention, there is provided a cutter head comprising:
at least two coaxial cutting wheels which rotate in opposite directions; and
at least
one cutting tooth extending substantially radially from each of said cutting
wheels; wherein a diameter of each of said cutting wheels tapers to one side
to
form a cutter head having an approximately round cross section; a pair of gear
plates for supporting said cutting wheels; wherein four cutting wheels are
supported in pairs, each pair of said cutting wheels being supported by one of
said gear plates.
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Further according to the invention, there is provided a boring jig for
boring into a surface, the boring jig comprising a boring jig for boring a
bore into
a surface, the boring jig comprising a cutter head for supporting at least one
cutting wheel, said cutter head including at least two coaxial cutting wheels
rotating in opposite directions and at least one cutting tooth extending
substantially radially from each of said cutting wheels, wherein a diameter of
each
of said cutting wheels tapers to one side to form a cutter head having an
approximately round cross section; and an elongated tube positioned above said
cutter head, said tube having a cross section corresponding approximately to a
bore cross section of the bore, said tube being extendable into the bore for
supporting bore sidewalls defining the bore; a pair of gear plates for
supporting
said cutting wheels; wherein four cutting wheels are supported in pairs, each
pair
of said cutting wheels being supported by one of said gear plates.
The invention also provides a process for sea bottom boring with a sea
bottom boring jig comprising the steps of providing a sea bottom boring jig
including a cutter head for supporting at least one cutting wheel, an
elongated
tube positioned above said cutter head and a work table for supporting said
cutter
head and said tube, said tube having a cross section corresponding
approximately
to a bore cross section, said tube being extendable into the bore for
supporting the
bore sidewalls; lowering a portion of the boring jig including the cutter
head, a
work table and a tube from an initial position to a predetermined position,
boring
into the sea bottom with said cutter head to form a borehole; advancing said
tube
in conjunction with an advancement of said cutter head into the borehole;
conveying cut material to a receptacle by a suction line; retracting said tube
and
said cutter head from the borehole; and raising the portion of the boring jig
including the cutter head, the work table and the tube to the initial position
after
the tube and cutter head have been retracted from the borehole.
The invention also provides a boring jig for boring a bore into a
surface, the boring jig comprising a cutter head for supporting at least one
cutting
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wheel; and an elongated tube positioned above said cutter head, said tube
having
a cross section corresponding approximately to a bore cross section of the
bore,
said tube being extendable into the bore for supporting bore sidewalls
defining
the bore; wherein said cutter head includes at least two coaxial cutting
wheels
rotating in opposite directions; and at least one cutting tooth extending
substantially radially from each of said cutting wheels; wherein a diameter of
each of said cutting wheels tapers to one side to form a cutter head having an
approximately round cross section; reaming plates associated with each of said
cutting wheels for interacting with said cutting teeth for grinding cut
material to a
defined, maximum particle size.
The boring jig according to the present invention yields a bore sample
that precisely reflects the depth placement of the tool and the particular
individual
materials desired. Additionally, very stable operating conditions are achieved
in
the borehole as a result of the substantially round bore cross section.
Furthermore, the surface area of the borehole wall is minimal compared to the
borehole volume. Accordingly, with the borehole shape according to the present
invention, high efficiency is achieved, i.e., a high yield of cut material is
conveyed.
Although the boring jig in accordance with the present invention can
also be used on land, it is especially suited for use as a sea bottom boring
jig.
A very good boring result is achieved if the cutter head is designed as a
full cut cutter head. Preferably, the cutter head is made of frustum-shaped
cutting
wheels that turn in opposite directions. This design makes it possible to
achieve a
circular bore cross section. As a result of this boring head design, the
boring head
exhibits a very high boring efficiency.
A further object of the present invention is to provide a boring head
which supports four cutting wheels in pairs on gear plates and to place
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hydraulic drive motors above the gear plates. Additionally, in order to
further
increase the bore head's efficiency, reamer plates are provided on the cutter
head. The reamer plates aid in grinding the cut material such that the cut
material can be ground up by the cutting teeth to a defined, maximum particle
size. The ground up, cut material can then be extracted through a suction box
by a suction line.
A boring jig according to the present invention includes, above the
cutter head, a tube with a cross section that corresponds approximately to the
bore cross section. Using this tube stabilizes the cutting head and secures
the
entire bore. The bore cannot cave in or be filled in because of slipping
material
surrounding the bore, so that a precisely preset ground area with defined
volume can be conveyed. The evaluation of such a sample bore is thus
especially reliable. Further, by utilizing the bore tube, the cutting head is
easily
advanced through the bore.
Especially good results are achieved if a cutter head according to the
present invention is used in conjunction with a work table that is supported
on
the bore surface and grasps the tube with a regrasping system for advancing
and
retracting the tube in a lengthwise direction of the tube. In particular, the
work
table with the regrasping system exerts a forward-pushing force on the cutter
head. This arrangement readily stabilizes the boring jig in a secure manner.
Further, when the boring head and the tube are pulled out, the forces
occurring
in the process are transferred directly to the earth surface around the bore
without stressing other components of the device.
To achieve efficient operation and to drain and feed the cutter head a
suction line and hydraulic line are each attached integrally within the tube
and
flushing water may be fed to the cutter head through the tube. This
advantageous use of the area surrounding the boring head guarantees a quick
and reliable carrying away of the cut material. Further, a lasting
facilitation of
the cutting conditions is achieved by the reliable outflow of loosened earth.
The design of the tube, which is made of for example steel or plastic,
protects
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the tool from damage caused by contact with sharp-edged projections of the
bored earth which are created during the boring process.
Since the most beneficial area for earth sampling often does not lie
directly under the earth's surface, an advantageous simplification of the
boring
operation is achieved by providing a bypass valve on the top end of the tube
through which unwanted cut material can be pumped out of the suction line.
This saves the expense of pumping the unwanted cut material through the entire
suction line up to the supply ship.
An advantageous application of the sea bottom boring jig is
guaranteed by mounting it on a ship with a work turret placed above an
opening positioned amidship. The part of the sea bottom boring jig that can be
lowered, which consists mainly of the cutter head, work table and tube, can be
retracted and deployed through the opening. The tube that has been pulled up
can be fastened securely in a vertical orientation, in the work turret.
Good boring operation is achieved by running lines through the top
opening of the tube to the cutter head, by way of guide devices on the work
table, for the operation of the sea bottom boring jig. This makes it possible
to
stretch these lines relatively tautly with minimum length and to avoid the
affects of the sea current, without an undesired force being exerted by these
lines upward on the boring head and the tube. The lines exert a force only
upward on the work table, which because of its weight, does not experience any
disruption in its orientation. Advantageous operation is further made possible
by providing a rope guided over rollers that connects the ship, the work
turret,
a sliding guide part surrounding the tube and the work table, to lower and
raise
the sea bottom boring jig. In doing so, rapid and precise boring is achieved.
In an especially advantageous way, the vertical orientation of the
tube can be maintained by the guide part if the rope is held constantly at a
relatively high tension. As already described above, the work table, because
of
its great weight, can be subjected to relatively high, upward-oriented forces
without its orientation being impaired.
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In accordance with the present invention, the aforementioned objects
are achieved by lowering the part of the sea bottom boring jig that consists
mainly of the cutter head, the work table and the tube through the opening
amidship, on the rope, from the recovery winch on the ship to the sea bottom,
with the work table being located on the bottom end of the tube; boring into
the
sea bottom with the cutting head with the regrasping system subsequently
advancing the tube downward; conveying the cut material up to the ship by a
suction line; and after the boring operation is finished, using the regrasping
system to pull the tube up and out of the borehole. The part of the sea bottom
boring jig that can be lowered subsequently pulled up again to the ship using
the recovery winch on the ship.
Thus, a sea bottom sampling system is provided that can convey
large volumes of sea bottom samples in a simple and fast way. Because of the
process, relatively great boring depths are possible, especially since the
bore is
secured through the tube and a secure orientation is provided by the heavy
work
table which is positioned on the sea bottom. During the boring process,
unwanted cut material may be removed by the bypass valve on the top end of
the tube out of the suction line without having to pump the unwanted material
up to the supply ship.
In overall operation, the boring head is reliably manipulated through
the tube in that large amounts of follow-up sea water as flushing water for
the
cutting operation is delivered to the cutting head.
Embodiments of the present invention will now be described with
reference to the accompanying drawings, in which
Figure 1 is a side cross sectional view of a boring head in accordance
with the present invention;
Figure 2 is a lengthwise side view of a boring head in accordance
with the present invention taken along line a-a of Figure 1;
Figure 3 is a side view of a supply ship illustrating the boring jig in
accordance with the present invention in both the raised position and the
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lowered position with a cross section of the sea bottom of the part of the
lowerable sea bottom boring jig according to the present invention during the
boring operation;
Figure 4 is a side view of the portion of the sea bottom boring jig in
accordance with the present invention which is lowered in the manner
illustrated in Figure 3;
Figure 5 is a top view of the lowerable portion of sea bottom boring
jig in accordance with the present invention;
Figure 6 is a perspective view of the portion of the sea bottom
boring jig illustrating the lowering and raising mechanism in accordance with
the present invention.
Detailed Description of the Present Invention
With reference now to the several figures, Figure 1 shows a cutter
head 1 having a substantially round bore cross section. The cutter head 1 is
preferably formed of four frustum-shaped cutting wheels 2 running in pairs in
opposite directions, as shown by the arrows, and are supported in pairs by two
gear plates 6. The radii of the frustums become smaller in an axial direction
from the axial center of the cutter head 1 outwardly. The cutting wheels 2
positioned axially on the outside of the cutter head 1 have a smaller diameter
than the inner cutting wheels 2. The cutting wheels positioned on the outside
of the cutter head 1 are formed from a first frustum, positioned axially
inside a
second frustum, which is flatter than the cone from which the frustums of the
inner cutting wheels 2 are derived with the second frustum being a smaller
frustum, lying axially outside the first frustum, which is of a still flatter
cone
whose small surface that forms the axial end is considerably smaller than the
greatest diameter of cutter head 1.
The drive motors for the cutting wheels 2 (not shown) are positioned
adjacent to and above the cutting wheels 2. The gear plates 6 are attached to
a
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frame 7 that is placed on the end of a tube 12 (Figure 3). As noted above, the
cutting wheels 2 run in pairs in opposite directions. Each pair of cutting
wheels
2 are driven by a gear similar to that shown in EP 0 167 090. A torque
occurring around the bore axis is compensated for by the firm supporting of
tube 12 in the circumferential direction within the bore. Cutting teeth 5 are
positioned about the circumference of cutting wheels 2, spaced evenly from one
another in the circumferential direction, which enlarges the working area of
the
cutter head 1 out to dashed delimitation lines 8 as shown in Figure 1.
For clarity, only a single cutting tooth 5 is illustrated as an example
in Figures 1 and 2. Figure 2 further shows a reaming plate 4 that grinds the
cut
material to a defined maximum particle size. The now cut and ground material
is suctioned off through a suction box 3 and a suction line 28.
The environment to which the present invention is most readily
adapted is illustrated in Figure 3. As Figure 3 shows, a ship 11 is provided
as
an above-water device for conducting the boring operation. The ship preferably
includes a work turret 16 amidship that is placed above an opening 18 in the
ship bottom. The portion of the sea bottom boring jig which is to be lowered
is lowered on a rope 26 through this opening 18 to a predetermined position.
This portion of the sea bottom boring jig includes the cutter head 1 (not
shown
in Figure 3), tube 12 and a work table 13. Figure 3 shows this part in both
the
idle position and in the work position, namely in the raised position, where
tube
12 is fixed in a vertical orientation in work turret 16 and in a lowered
predetermined position, where tube 12, by a regrasping system 14, is pushed
down relative to work table 13 to the maximum bore depth.
The regrasping system 14 consists of hydraulically driven clamps that
are adjustable in the radial direction and in the axial direction of tube 12.
The
clamps grab onto the circumference of tube 12 and move it in the axial
direction. The clamps are pressed with the hydraulic drive in the radial
direction against tube 12 so that they are securely pressed against the
circumference of tube 12 without being able to slip relative to the tube 12.
The
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clamps are distributed around the tube circumference approximately evenly so
that no resulting moment acts in the radial direction on tube 12. To move tube
12, the clamps are hydraulically driven in the axial direction of tube 12,
causing
them to take tube 12 along with them and to shift it relative to work table
13.
If tube 12 is to be shifted relative to work table 13 further than the maximum
lift of the clamps in the axial direction, the clamps loosen themselves from
tube
12 when the maximum lift in the axial direction is reached, are then moved
back in the opposite direction and then grip tube 12 again by a movement in
the radial direction. Then the clamps carry tube 12 along with them again in
the desired direction of movement.
The tube 12 has a diameter that corresponds to the bore diameter of
the cutter head 1. During the boring operation, the force transmitted by the
regrasping system from work table 13 to tube 12 in the axial direction of tube
12 acts as the force to advance the cutter head 1. In particular with sea
bottom
boring, tube 12 results in improved boring conditions since, due to the
extremely free-flowing components of the sea bottom, the bore is always
subjected to the danger of filling up due to collapsing of the side walls.
Since
tube 12 has no projections and relatively flat walls, its insertion into the
bore is
possible with a relatively small exertion of force. The cutter head 1 is held
by
tube 12 in a straight boring direction. This makes it possible to conduct
sample
bores in precisely defined areas. The cutter head 1 and tube 12 are integrally
connected to one another. The tube 12 thus also fulfils a support function for
cutter head 1. The tube cross section is matched to the approximately circular
bore cross section of cutter head 1. Because of this cross sectional shape,
the
stability of tube 12 against caving in or buckling is very high.
On the top end of tube 12 there is a bypass valve 15 through which
unwanted cut material can be pumped out of suction line 28. This bypass valve
15 makes it possible, for example, to empty the cut material that was bored in
the first section of the bore and to raise to ship 11 only the cut material
that
comes from a deeper bore depth. After the end of the boring operation tube 12,
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with cutter head 1, is again raised relative to work table 13 by regrasping
system 14. Typical retraction forces are on the order of 500 to 1,000 tons.
But
the latter are not introduced into rope 26 between ship 11 and work table 13.
Only after tube 12 has been raised completely relative to work table 13 is the
rope 26 wound up by a recovery winch 25 (see Figure 6) on the ship.
Referring now to Figures 4 and 5, the tube 12, on the lower end of
which cutter head 1 (not represented) is located, is connected to work table
13
by regrasping system 14. The tube diameter typically is about 2 meters and the
tube length is generally a maximum of about 30 meters with the weight of
work table 13 being about 120 tons. It should be appreciated that both larger
and smaller dimensions can also be employed. The work table 13 and the tube
12 are connected to one another by a universal suspension 27, such that the
boring jig can conduct a vertical bore even when positioned on a slanted sea
bottom. A hydraulic line 20 and suction line 28 run from the cutter head 1
upward through the inside of tube 12, out of tube 12 on its upper end, then
parallel to tube 12 downward to guide devices that consist of guide rollers 17
attached to work table 13, and then again up to ship 11. The tube 12 also
forms a conduit for flushing water to supply flushing water to the cutter head
1.
The hydraulic line 20 and suction line 28 are preferably metal tubes inside
the
tube 12 and on the semicircular guide parts on the top end of the tube, so as
to
reduce their susceptibility to torsion. Inside the upper part of tube 12 there
is
also a height adjustment 30 for a guide part 24 that surrounds tube 12.
As Figure 6 shows, rope 26 runs from the recovery winch 25 on the
ship, over a roller on a work turret top part 23 on the ship, through an
opening
of guide part 24, to two rollers on work table 13, then it goes again through
guide part 24 to work turret top part 23 on the ship, then again to work table
13 and finally again back to work turret top part 23 that is on the ship and
to
which the rope end is attached. During the boring operation on the sea bottom,
the distance between work table top part 23 on the ship and guide part 24 is
greatly increased relative to that represented in Figure 6. For example, the
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device works at a water depth of up to about 200 to 300 meters. This distance
then corresponds also to the distance between work turret top part 23 on the
ship and guide part 24.
The guide part 24 is adjustable in height relative to tube 12 by height
adjustment 30. The height adjustment 30 is used to lower the guide part 24
when the tube 12 is completely raised up in the work turret 16. In the fully
raised position, tube 12 exceeds the height of work turret 16 and thus also
the
height of work turret top part 23 on the ship, so that guide part 24 can no
longer be located on the top end of tube 12. When tube 12 is lowered, guide
part 24 is generally as far up on tube 12 as possible to achieve a good
vertical
guiding for tube 12 with the rope 26 being under relatively high tension. The
height adjustment 30 consists of two diametrically opposed guide rollers 31 on
the top edge of tube 12. Driven winches 32 (only one winch 32 is illustrated)
are placed inside the tube 12, near the top edge, under both guide rollers. A
rope extends from the winches over guide roller 31 downward on the outside of
tube 12 to an attachment point on guide part 24 and lying in each case next to
tube 12. The guide part 24 is shifted in the axial direction relative to tube
12
by the rolling up and letting out of the rope by height adjustment 30.
The operation of the above described sea boring jig will now be
described in detail hereinbelow.
The ship 11 travels over a point on the sea bottom that is to be
sampled. During the trip the sea bottom boring jig is in the raised position
and
located in the work turret 16. When the ship 11 has stopped and is aligned
vertically with the area to be sampled, the part of the sea bottom boring jig
that
is to be lowered is lowered through the opening 18 from work turret 16 into
the
water down to the sea bottom. The work table 13 is located during this
operation on the lower end of tube 12. Thus, the work table 13 reaches the sea
bottom first and assumes a stable orientation because of its substantial
weight.
The rope 26, hydraulic line 20 and suction line 28 are stretched
between the ship 11 and the lowered portion of the boring jig. The rope 26
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runs along the tube 12 through the guide part 24 which, after tube 12 has left
the work turret 16, is moved to the top end of tube 12. In doing so, because
of
the relatively tautly stretched rope 26, a vertical orientation of tube 12 is
maintained by the guide part 24. The rope 26 can be stretched relatively
tautly
without the heavy work table 13 being lifted. With an uneven sea bottom, even
if work table 13 is lying at a slant, a vertical orientation of tube 12 can be
maintained, since both these parts are connected with universal suspension 27.
Next the actual boring operation is conducted by moving the cutting
wheels 2 in the turning direction. The cutting wheels 2 rotate in pairs in
opposite directions. The cut material is grasped by cutting teeth 5 and ground
up by the cooperation of the reaming plates 4. The ground up cut material is
withdrawn through the suction box 3 and suction line 28 and raised to ship 11.
There it is collected and analyzed.
The advance of the bore of cutter head 1 into the sea bottom is
effected by the regrasping system 14 on work table 13, which pushes tube 12
downward in accordance with the speed of the bore advance. During the
boring operation, drive energy is transmitted to the cutter head 1 by the
hydraulic line 20 and sea water is fed through tube 12 for flushing the bored
area. Optionally, a part of the cut material can be removed through the bypass
valve 15 on the top end of tube 12 out of the suction line 28 without having
to
be raised to ship 11. The maximum bore depth is established by the length of
the tube 12. If the tube 12 is grasped by the regrasping system 14 on its top
end, the maximum bore depth is reached and the tube 12 is again pushed
upward by the regrasping system 14. Afterward, the part of the sea bottom
boring jig that can be lowered is raised by rope 26 again to the ship 11 into
work turret 16. The boring operation is ended and ship 11 can leave the boring
site.
Accordingly, as can be appreciated from the foregoing description,
the boring jig according to the present invention yields a bore sample that
precisely reflects the depth placement of the tool and the particular
individual
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materials desired. Additionally, very stable operating conditions are achieved
in
the borehole as a result of the substantially round bore cross section.
Furthermore, the surface area of the borehole wall is minimal compared to the
borehole volume. Accordingly, with the borehole shape according to the
present invention, high efficiency is achieved, i.e., a high yield of cut
material
is conveyed with this cut material being only that material intended to be
conveyed.
While the present invention has been described with reference to a
preferred embodiment, it will be appreciated by those skilled in the art that
the
invention may be practised otherwise than as specifically described herein
without departing from the spirit and scope of the invention. It is,
therefore, to
be understood that the spirit and scope of the invention be limited only by
the
appended claims.
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